Malloc of arrays and structs within a struct

Question

How does one malloc a struct which is inside another struct?

I would also like to malloc an array of items inside a struct and then realloc this array when needed, how i

Answer 1

typedef struct _A { int i; } A;
typedef struct _B { int j;  A a} B;

To get a single B:

B *b = malloc(sizeof(B));

To get an array of B:

B *b = malloc(sizeof(B) * arrayLength);